A tactic I'd like to try is Icon of Tzeentch bikers with two meltas and a power weapon/fist champ possibly used in conjunction with deep striking Oblits x 3 backing them up. 2++ turbo-boost is nothing to be sniffed at... Then next turn, and with a decent reserves roll the unlucky broadsides are facing myriad possibilities for shooty death. How does 5 melta shots, 3 twin linked followed by a hellish charge strike you? Well, other than brutally hard............Then your bikes can zoom off again, and you have a shiny new firebase in the form of obliterators. Huzzah!